Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A variety of physiological parameters of a human body can be detected and used to determine a health state or other information about the body (e.g., to determine a blood sugar level, to determine a blood pressure, to determine that the body is in danger from an adverse health state) and/or to perform some activities relating to the body (e.g., to inform a drug dosage, to decide a course of medical treatment, to adjust an athletic training regimen). Such physiological parameters can be detecting at a plurality of points in time and/or across an extended period of time by body-mountable devices that include sensors and other electronic components configured to measure one or more physiological parameters and/or to perform some other functions, e.g., to log and/or record measured physiological parameters, to indicate (e.g., transmit) measured physiological parameters to an external system, or to perform some other function. Such body-mountable devices can be powered by on-board batteries, by energy transmitted from an external system (e.g., transmitted RF energy), by environmental power sources (e.g., motion of the body-mountable device, flexion of the body-mountable device), or some other power source.